Planets are turning out to be so common that to show all the planets in our galaxy, this chart would have to be nested in itself--with each planet replaced by a copy of the chart--at least three levels deep.

"Exoplanets", by Randall Munroe, licensed under Creative Commons Attribution-NonCommercial 2.5 License

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Planets are turning out to be so common that to show all the planets in our galaxy, this chart would have to be nested in itself--with each planet replaced by a copy of the chart--at least three levels deep.